Aqueous colloidal polymer dispersions of biodegradable DL-lactide/glycolide copolymer as basis for latex films: A new approach for the development of biodegradable depot systems

Abstract

While biodegradable polymers are usually used for the preparation of drug-loaded nanoparticles, we studied the application of biodegradable polymers in the form of aqueous colloidal polymer dispersions for the preparation of latex films. We consider biodegradable latex films as a new interesting approach for the development of pharmaceutical preparations such as the coating of core materials for subcutaneous application. Aqueous colloidal dispersions of the biodegradable DL-lactide/glycolide copolymer (PLGA) were prepared by a spontaneous emulsification solvent diffusion method. Drying of the aqueous colloidal polymer dispersions led to the formation of PLGA latex films. The properties of these PLGA films and the influence of plasticizers were investigated using thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). It was found that polyethylene glycol 1500 (PEG 1500) and triethyl citrate had a good plasticizing effect, decreasing significantly the glass transition temperature ( T g ) of the PLGA latex films. The T g value determined via TMA was higher than that with DSC measurement. It was suggested that DSC might be useful to detect the mobility of plasticizer molecules, whereas TMA could be helpful in detecting the changes in the mechanical properties of films induced by heat. Further, it was found that the amount of residual organic solvent in the present PLGA latex films was below the sensitivity of the assay (gas chromatography).